CA1131843A - Acidified electrodepositable michael adducts of polymers - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A heat-curable resinous binder dispersible in aqueous medium with the aid of cationic salt groups and electrodepositable on a substrate comprising the Michael-type reaction product of:
(A) an active hydrogen-containing polymeric material containing alpha, beta-ethylenically unsaturated moieties in conjugation with moieties with (B) a primary and/or secondary amine having a boiling point below 100°C;
said reaction product being treated with an acid to provide said cationic salt groups and being in combination with a curing agent which is reactive with the active hydrogens at elevated temperatures to form a crosslinked product.

Description

~.3~

MIC~EL ~DDUCTS OF POL~MERIC MATE'RI~LS
U5EFUL IN EI,ECTROCOA~ING ~PPLICAT'IONS

~ ention Field of the Invention: 'rhe present lnvention relates to curable resinous binders which are acidifled Mlchael adducts of (A) polymeric materials contaîning alpha, be~a-ethylenically unsaturated moieties in conjugation with - C - ~ - moieties and (B) primary a~d/or O H
secondary amines and to the use of these binders in cationic electrodeposition.
Brief ~escription of the Prior Art: It is known in the art that resinous materials can be dispersed in water with cationic ~roups such as quaternsry ammonium base groups and amine salt groups. Such resinous ma~erials can be used as binders for wa~er-based coating compositlons which can be deposited on substrates by flow9 dip, spray and roll coating as ~ell as by cationic electrodepo~ition. One disadvantage of such cationic systems is the presence of the amino nitrogen ~hich severely discolors white and pastel coatings and gives the coating a basic character wh1ch inhibits ~-acid catalyzed cures such as with aminoplast crosslinking agents, It is an ob~ect of the present invention ~o provide a cationic resinous binder fo~ use ia aqueous based curable coating compositions which are hydrolytically stable9 which do not severely discolor white or pastel coatings and can be cured at relatively low temperatures with aminoplast crosslinking agents.

sulml,ary o~
In accordance with the presen~ invention, a resinous binder which is dispersible ln aqueou~ medium with the aid of cat~onic salt groupg and whic~
i5 electrodepositable on a subs~ra~e i9 provided. Thle reglnous binder co~pri~es ~hc reaction product of:
(A) a polymeric materlal containing alpha, beta-s~hylenically unsaturated molaties in conjugation witb - C - N - moieties wi~h " t . 0 H
(B~ a pxlmary and/or secondary amine;
said reacticn product being aeutralized with an acid to provide lo cationic salt groupA.
The resinous binders can be used in ca~ionic electrodeposition.
They are hydroly~ically stable~ they do not severely discolor whit~ or pas~el coatlng~ and ~hey can be cured at relatively low temperatures with aminopla~t cros~linking agents.

More pa~tioularly, the invention provides a heat-~urable resin-ous binder dispersible in aqueous medium with th0 aid of cationic salt groups and electrodepositable on a substrate comprising the Michael-type reaction product of:
tA) an active hydrogen-contalning polymeric materisl contalning alpha, beta-ethylenically unsaturated moieties in con~ugation with - C - N - moietias with 1~ 1 (B) a primary and/or secondary amine having a ~oiling poin~ below 100C;
said reaction product being tre~ted wieh an acid to provide said cationlc salt groups and belng in co~bination with a curing agen~ which ls reactlve with ~he actlve hydrogens st elevated temperatures ~o form a crossllnked product.

~3~3 Prior Art U.S. Patent 3,975,251 to ~c~ilmiss disclose~ cationic electro-depositable compositions comprising acid~solubilized polyamine re~ins in combination with polyacrylate curing agents~ Upon elec~rodeposition, the polyamine resin deprotonates on the cathode, expo!3ing primary or secondary amine groups which react via a Michael addition with the poly-acrylate curing agent to form a cured coating. In such compositions, the polyamine resin must be compl~tely neutralized to prevent any premature reaction between the unprotonated polyamine rasin and the polyacrylate curing agent ln the elec~rodeposition b~th. Complete neutrallzation is a disadvantage in that it may result in ba~hs with low pH's which can cause corrosion proble~s~ In addition, in the resinous compositions of the -2a-~3~ 3 ~cGinniss patent, the amine groups are not released on curing and thus th~
resultant electrodeposited coatin~s are not readily c~rable by ~utooxida~ion or with amine-aldehyde curing agents.
U.S. Paten~ 3,637,597 eo Jalics discloses water-dispersible polymers containing pendan~ ~annich adduct units for rendering the polymer dispersible in wnter. The polymer can be deposited as a ~llm. When the film is heated, ~he Mannich adduct units decompose leaving a less basic film and unsaturated sites for subsequent curing via vinyl polymeriza~ion.
Austrian Patent 344,840 discloses Michael-typ& reaction of a primary or secondary amine with a poly~erlc material containing C = C -- C --O
moieties. These reaction products can be acidified and used in cationic electrodeposition. Cure is through the vinyl groups.

Detailed Description The resinous compo~itions of ~he present in~e~tion comprise a polymeric material which is formed via a Michael-~ype reaction o a primary and/or secondary amine wi~h a polymeric material containing H

.
C ~ C - C - N -O

moleties. These resinous compositions have improved hydrolytic stability over the resincus compositions of Austrian Patenc 344,840. ~

The polymeric materials optionally contain active hydrogens, e.g.
hydroxyl groups such as those selected from the class consisting of pri~ary amine, secondary amlne (including i~ine), thiol a~d carboxylic acid.
Such polymeric ~aterlals are curable with acrosslinking agent such as an ~3 ~ 3 amine~aldehycie condensclte or a capped lsocyarlaee. To introduce the alphcl, beea~eehy:lenicall.y un~saturated moleties in conJugation wieh - C - N - mo:Leties, ~he hydro~yl-coneaining polymeric material can be " ~ , 0 ~1 transetherified with N-allcoxymethyl-c~on~aining acrylamides or methacrylamides such as N-butoxymethylacrylclmide and N-ethoxymethy:LmethacryIamide.
Preferred hydroxyl-containing polymeric materials are hydroxyl-containing epoxy resins and more preerably hydroxyl-containing polymeric materials derived from epoxy resins such as epoxy resins defunctionalized with alcohols or polyols to form polyetherg.
The epoxy-containing resinous materials are polyepoxides, that is, epoxy resins which have a 1,2-epoxy functionality greater than one.
The preferred polyepoxides are polyglycidyl ethers of polyphenols preferably bisphenols such as ~isphenol A. These can be produced, Eor example, by etherification of polyphenol with epihalohydrin or dihalohydrin such as epichlorohydrin or dichlorohydrin in the presence of alkali. The polyphenol can be, for example, hydroquinone, 2,2-bis-(4-hydroxyphenyl)propane, 1,1-bis-(4-hydroxyphenyl)ethane, 2-methyl-1,1-bis-(4-hydroxyphenyl)propane,

2~2-bis-(4-hydroxy-3-tertiarybutylphenyl)propaIIe, bis-(2-hydroxynaphthyl)-methane, 1~5-dihydroxynaphthalene or the like. Also oxyalicylated adducts such as ethylene and propylene oxide adducts of polyphenols may be employed.
Another quiee useful class of polyepoxides is produced from novolak resins or similar polyphenol resins.
The polyepoxides such as the preferred polyglycidyl e~hers of polyphenols can be further reacted to chain extend and increase their molecular weight. For example, they may be further reacted with active hydrogen-containing materials, which are, oE course, different from the polyglycidyl eeher of the polyphenols and which are reactive with epoxy ~..
~'~' groups, S~lCil as those con~aining hydroxyl, thiol, carboxylic acid~ prlmary and secondary amine groups. Preferred chain extenders are organic polyols, preferably polymeric polyols. Chain extending of epoxy-containing polymeric materials with polymeric polyols is disclosed in U.S. Patent 4,148,772. The epoxy~containing polymeric materials can also be chain extended with N-heterocyclic-containing materials such as described in U.S. Patent 4,110,287.
Besides the polymers mentioned above, other epoxy-containing polymers can be employed although their use is not preferred. Examples include polyglycidyl ethers of polyhydric alcohols, polyglycidyl esters of polycarboxylic acids and epoxy-containing acrylic polymers. These polymers are described in U.S. Patent 4,001,156 to Bosso and Wismer.
Besides the hydroxyl-containing, epoxy-containing resinous materials described, hydroxyl-containing polymeric materials prepared from the epoxy resin can be used. Such hydroxyl-containing polymeric materials would beg for example, the reac~ion product of the epoxy resins with monoalcohols, phenols or excess polyols to give epoxy-free pDlyether polyols. It is preferred that the polymeric polyol be epoxy free to avoid subsequent reaction of the epoxy functlonality with primary and/or secondary amine. ~xamples of other hydroxyl-containing polymeric materials are hydroxyl-containing acrylic polymers such as described in U.S. Patent

3,403,088 to Hart and hydroxyl-containing polybutadienes.
As mentioned above, the C = C - C - N -/ O H
moieties can be introduced into the polymeric material by transetherifying the hydroxyI-containing polymeric material with N-alkoxymethyl acrylamides or methacrylamides.

~3~

The hydroxyL-containing polymer and the N-alkoxymethyl~
acrylamide ara heated at 50-200C., preferably ~0--160~C. usually in the presence of free radical inhibitors and preEerably about one percent by weight of an acid catalyst such as p-toluenesulfonic S acid. Preferablyg the transetherification is driven to completion by removal of the evolved alcohol by distillatio~ at atmospheric or reduced pressure. ~Lternately, the evolved alcohol can be removed as an azeotrope with another solvent, preferably one free of hydroxyl groups.

~3~3 The amount o:E alpha, beta-e~hylerlically unsaturated moieties in conjugatlon w:ith - C - N - moieties should preferably amount to an ,. -O H
average of 0.1 to 10, more preferably 0.5 to 5 equivalents of unsaturation per mole o:E polymeric material.
The amine which is reacted with the polymeric material contalning C = C - C - N -/ O H
moieties to form the Michael adduct is a primary or secondary amine which is volatile under curing conditions. When a coating composition containing the polymeric Michael adduct is deposited on a substrate to form a film and:~he film heated to curing temperatures, the Michael adduct decomposes reieasing free amine which volatilizes under curing conditions, that is, at least 25, preferably at least 50, and most preferably at least 80 percent by weight of the amine volatilizes leaving a less basic (or even neutral) film. Examples of primary and secondary amines are those which have a boiling point below 200C. and examples include ethanolamine, methyl ethanolamine, piperidine and amylamine. Preferred primary and secondary amines are.those boiling below 100C. such as propylamine, diethylamine and dimethylamine.
~ The condi~ions under which the amine and the-polymeric material containing C - C - C - N -~ " ' , / O H
moieties are reacted are as follows:
To the.stirred mixture of the polymeric material containing C = C -- C -- ~ --- .
O H

. .

~ 3~

~oieties and a~ly desired solvent to reduce viscosity, the a~ne is added.
The reaction temperature can be initially ambient temperature or sligh-tly above ~i.e., 50C.). Cooling may or may not be necessary dependlng on the e20thermic nature of the particular reaction and the scale on which it is conducted. Following amine addition, reaction is carried to comple~ion by heating at 50-80C. for 1 to 2 hours.
Secondary a~ines are preferred to primary amines because of processing conditions. Primary amines are difunctional and have potential for gelling the reaction mixture. If primary amines are used, precautions should be taken to avoid gelling. For example, excess amine can be used and the excess vacuum stripped at the completion of the reaction. Also, the above-described reaction condltions can be varied such that ~he polymeric material is added to the amine.
The ratio of amine to polymeric material conraining C = C - C - ~ - -/ H
moieties should preferably amount to at~least 0.1, more preferably from 0.1 to 1 equivalents of amine to 1 equivalent of , C - C - C - N -moieties.
The Michael adducts prepared as described are made water dispersible by the inclusion of cationic groups such as amine salt groups in the ~ichael adducts~.
Amine salt groups can be obtained by neut~alizing the Michael adduct with acid. Example5 o suitable acids include organic and inorganic acids such as formic acid, acetic acid, lactic acid, phosphoric acld and ' carbonic acid. lhe extent o~ neutralization will depend on the particular Michael adduct employed. It is only ~ecessary that suffic;ent acid be added to solubilize or disperse the product in waLer. Typically, the amount of acid used will be sufficient to provide about 30 to 120 percent of ehe total theoretical neutraliæation.
For aqueous-based systems, the concentration of caeionic groups, the molecular weight and the structure of the resinous binder should be coordinated with one ano~her such ~hae when the resinous binder is mixed with an aqueous medium, a stable dispersion will formO A stable dispersion is one which does not sediment or is one which is easily re- -dispersible if some sedimentacion occurs. In addition, the dispersios should be of sufficiellt cationic character that the dispersed resin particles will migrate towards the cathode when an electrical potential is impressed between an anode and a cathode immersad in the aqueous dispersion.
Also, the molecular weight, structure and concentration of cationic groups should be controlled so that the dispersed resin will have the required flow to form a film upon the substrate, and in the case of electro-deposition~ to form a film on a ca~hode. The film should be insensitive to moisture. For cationic electrodeposition, it should be insensitive to moisture to the extent th~t it will not redissol~e in the electrodeposition bath or be rinsed away from the coated cathode after its removal Erom the b~th. The structure, ~olecular weight and concentration of cationic groups are dependent-on one another and the selec~ion of one can only be made after a consideration of the other two. For example, because of flow considerations- andlor dispersibility, Michael adducts prepared from poly-glycidyl ethers of polyphenols should be of lower molecular weight than _ g _ many of the hydroxyl-con~ainlng acryLic polymers mentioned above. In addl~lon, higher molecular weight polymers usually require a higher concentration of cationic groups than lower molecular weight polymers unless the polymers contain hydrophilic groups such as poly(oxyalkylene) moieties.
In general, most of the Michael adducts useful in the practice of the invention have molecu}ar weights within the range of 500 to 60,000.
Water dispersible adducts will usually contain from about 0.01 to 10 milliequivalents of cationic groups per gram of resin solids. ~ith regard to the polymers prepared from the preferred polyglycidyl ethers of the-polyphenols, the molecular weight of the preferred polymers will fall within the range of 500 to 10,000, more preferably 1000 to 10,000. For aqueous systems, these preferrecl polymers will contain from about 0.01 to 8.0 and preferably from about 0.05 to 6.0 milliequivalents of cationic groups per gram of polymer.
The preferred Michael adducts prepared in accordance with the ~ -present invention also contain active hydrogens whicn are-reactive at elevated te~peratures with a curing agent. Examples of active hydrogens are hydroxyl, thiol, primary amine, secondary amine (including imine) and carboxyl, with hydroxyl being preferred.
The curing agents are those which are capable of reacting with the active hydrogens to form a crosslinked product. Examples of suit-able curing agents are phenolic resins, aminopLasts and polyisocyanates.
The polyisocyanates should be capped or blocked so that they will not prematurely react with the active hydrogens in the Michael adduct.
The aminoplasts are aldehyde condensation products of melamine, benzoguanamine, urea or similar compounds. Generally, the aldehyde employed is formaldehydP, although useful products can be made from . .. , . . _ . . . . . . . .. ..

~3 IL~3~3 other aldehydes such 9S acetaldehyde, crotonaldehyde1 acrolein, benzaldehyde, furfural and others. Condensation products of melal~ine, urea or benzoguan-amine are most common and are preferred but products of other amines and amides in which at leasc one amino group is present can also be employed.
For example, such condensation products can be produced frGm various diazines, tria~oles, guanidines, guanamines and alkyl and di-substituted derivatives of such compounds including alkyl and aryl-substituted ureas and alkyl and aryl-substituted melamines and benzoguanamines. Examples of s~ch compounds are N,N-dimethyl urea, N-phenyl urea, dicyandiamide, formo-guanamine, acetoguanamine, 6-me~hyl-2,4-diamino-1,3,5-triazine, 3,5-diamino- -triazole, triaminopyrimidine, 2,4,6-triethyl~riamine-1,3,5-triazine and the like.
These amine-aldehyde and amide-aldehyde condensation products contain methylol groups or similar alkylol groups depending upon the particular aldehyde- employed. If desired, these methylol groups can ~-be etherified by reaction with an alcohol. Various alcohols are employed for this purpose including essentially any monohydric alcohol, although the preferred alcohols contain from 1 to 4 carbon atoms such as methanol, ethanol, isopropanol and n-butanol.
The aminoplast curing agent usually constitutes about 1 to QO and preferably 5 to 40 percent by weight of the resinous composition based on total weight Qf the Michael adduct and aminoplast.
The capped or blocked isocyanates which may be employed in the co~positions of the present in~ention may be any isocyanate where the isocyanato groups have been reacted with a compound so that the resultant capped isocyanate is stable to ac~ive hydrogens at room tempersture, that iS9 20 to 30C~, but reac~ive with active hydrogens at elevated temper-atures, usually between about 90-200C.

In the preparation of the capped organic polyisocyanate, any suitable organic polyisocyanate including aliphatic, cycloaliphatic and aro~atic polyisocyanates may be used. Examples include tetra-methylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexyl methane diisocyanate, 2,4- or 2,6-toluene diisocyanate and mixtures tbereof.
Higher polyisocyanates can be employed such as triisocyanates~
~ny sui~able aliphatic, cycloaliphatic, aromatic alkyl mono-alcohol and phenolic compound may be used as a capping agent in accordance uith the present invention, such as, for example, lower aliphatic alcohols contain-ing from 1 to 4 carbon atoms such as methanol and ethanol; cycloaliphatic alcohols such as cyclohexanol; aromatic alkyl alcohols such as phenyl carbinol. Higher molecular weight~ relatively non-volatile mono-alcohols such as 2~ethylhexanol can be used, if desired, to serve as plasticizers in the coating provided by this invention.
~dditional capping agents include oximes such as methyl ethyl ~-ketoxime and lactams such as epsilon-caprolactam. Use of oxi~es and lactams is particularl,v desirable because the polyisocyanates blocked with these agents unblock and react at relatively low temperatures.
The reaction between the organic polyisocyanate and a capping agent is usually exother=icl therefore, the polyisocyanate and the capping agent are preferably atmixed at temperatures of no higher than 80C. and preferably below 50C. to minimi~e the exotherm effect.
The polyisocyanate curing agent can be used in two similar ways.
The polyisocyanate can be fully capped, that is, no free isocyanate groups remain~ and ~hen combined with the polymeric Michael adduct to form a two-component system. Or, the polyisocyanate can be partially ~ca ~ ,~for example, a half-capped diisocyanate so that reactive isocyanate groups remain. The partially capped isocyanate can then be reacted with ~ portlon of the active hydrogans in the polymer mo:Lecule under conditions which will not unblock the isocyanate nor gel the reaction mixture. This reaction makes the capped isocyanate integral with the polyoer molecule.
Whether partially capped or fully capped, sufficient polyisocyanate i5 present in the coating system so that the equivalent ratio of latent curing capped isocyanate groups to active hydrogens is at least 0.05:1 and preferably about 0.1 to 1:1.
Besides the aminoplast and capped isocyanate curing agents which cure through reaction with the active hydrogens of the polymeric material, unsaturated curing agents whlch cure through reaction with the alpha, beta-ethylenic unsaturation in the polymer material can be employed. SeIf-curing systems in which the polymeric material polymerizes with itsel through the alpha, beta-ethylenic unsaturation are also possible although curing with additional unsaturated curing agents is preferred. E~amples of suitable unsa~urated curing agents are vinyl compounds which are non-vola~ile under curing conditions containing at least one CH2=C ~group.~ ~xamples of suitable vinyl compounds are divinyl benzene, methylene-bis-acrylamide and allyl ethers of mono-, dl- and trlmethylol phenols, particuLarly mi2tures thereof3 ànd more particlllarly mixtures thereof where the t~imethylated derivative is the predominan-t component of the mixture.
The unsaturated crosslinking agent generally constitutes about 1 to 60 and preferably 2 to 50 percent by weight of the composition based on total weight of the Michael adduct and crosslinking agent.

~3~ 3 For aqueous-based system~, the unsaturated crosslinking agent containing acryloyl or methacryloyl groups can be made cationic in character by reacting with a primary or secondary amine and neutrali~ing with acid as described generally abova.
~utooxidative curing is possible in the practice oE the invention.
Generally, o~idative curing is not possible with amine group-containing resins since amines inhibit oxidative cure. However, in the present invention, the amine is volatilized. E~amples of materials which are capable of oxidative cures are hydroxy-terminated transetherified polybutadienes with ~I-alkox~methyl acrylamides or methacrylamides as generally described above. As is conventional with autooxidative curing, metal driers such as heavy metal soaps, for example, cobalt and manganese naphthanate and octoate can be used.
The resinous compositions of the present invention, as mentioned above, are used in aqueous dispersions The term "dispersion" as used --with-in the context of the present invention is believed to be~a two-phase, transparent, translucent or opaque aqueous resinous system in which the resin is the dispersed phase and water is the continuous phase. A~erage particle size diameter of the resinous phase is generally less than 10 and preferably less than 5 microns. The concentration of the resinous phase in the aqueous medium depends upon the particular end use of the dispersion and in general is not critical. For example, the aqueous dispersion preferably contains at least 1 and usually from about 5 to 50 percent by weight resin solids.

3~

~esides wa~er, the aqueous medium may contain a coalescin~ solvent.
The use of coalesc;ng solvent may be, in some ins~ances, for improved film appearance. rhese solvents include hydrocarbons, alcohols, esters, ethers and ketones. The preferred coalescing solvents include mono-alcohols, glycols and polyols as well as ke~ones and other alcohols. Specific coalescing solvents include isopropanol, butanol, isophorone, 4-methoxy-2-pentanone, ethylene and propylene glycol, the monoethyl, monobutyl and monohe~yl ethers of ethylene glycol and 2-ethylhexanol. The amount of coalescing solvent is not unduly critical and i8 generally between about 0.01 and 40 percent by weight, preferably about 0.05 ~o about 25 percent by weight based on total weight of aqueous ~edium.
In most instances, a pigment composition and, if desired, various additives such as surfactants or wetting agents are included in the dispersion.
Pigment composition may be any of the conventional types comprising, for example, iron oxides, lead oxides, strontium chromate, carbon black, coal dust, titanium dioxide, talc, barium s~lfate, as well as color pigments such as ~admium yellowJ cadmium red, chromium yellow a~d the like. Pigment content of the dispersion is usually expressed as pigment-to-resin ratio~
In the practice of the present invention, the pigment-to-resin ratios are us;ally within the range oi 0.1 to 5:1. The other additives mentioned above are present in the dispersion in amounts of 0.01 to 3 percent by weight based on total weight of resin solids.
When the aqueous dispersions described above are employed for use in electrodeposition, the aqueous dispersion is placed in contact with an electrically conductive anode and an electrically conductive cathode with the surface to be coated being the cathode. Following conta~t with the aqueous dispersion, an adherent film of the coating _ 15 -1~.3~

composition is deposited on the cathode when sufficient voltage is imp~essed between the eLectrodes. The conditions under which electrodeposition is carried out are, in general, similar to those used in electrodeposition of othe~ types of coatings. The applied voltage may be varied and can be, S Eor example, as low as one volt or as high as several thousand volts, but typically between 50 and 500 volts. The currene density is usually between 1.0 ampere and 15 amperes per square foot and tends to decrease during electrodeposition indicating the formation of an insulating film.
The curable resinous compositions of the present invention can also be used in other conventional coating applications such as flow, dip, spray and roll coating.
For electrodeposition and other conventional coating applications, the coating compositions can be applied to a variety of electrocoaductive substrates especially metals such as steel, aluminum, copper, magnesium and the like, but also include metallized plastic and conductive carbon-coated --materials. For other conventional coating applications, the compositions can be applied to non-metallic substrates such as g]ass, wood and plastic.
After the coating has been applied, it is usually cured by baking at elevated temperatures such as 90 to 210C. for about 1 to 30 minutes.
Illustrating the invention are the following examples, which9 however, are not to be construed as limiting the invention to their details. ~11 par~s and percentages in the examples as well as throughout this specification are by weight unless otherwise indicated.

- 16 ~

~l~3~ 3 ~ e I
A polyepo~ide (polyglycidyl ether of Bisph~nol A) was defunction-alized with trimethylolpropane. The resulting polymeric pol~ol was reacted w-ith N-butoxymethyl~crylamlde to form a polymerlc material containing C = C - C - N -~ 1, , ~ O H
moieties. The Michael adduct was prepared by reacting this polymeric mate~ial with dimethylamine. The charg& for preparing the reaction product was as follows:

Ingredient SolidsParts by Weight l*
EPON 829 859.0 895.0 Bisphenol A 289.0 289.0 trimethylolpronane 215.0 215.0 stannous chloride (catalyst)2.5 2.5 dibenzyl ether 50.0 N-butoxymethylacrylamide 400.0 400.0 hydroquinone (free radical inhibitor) dissolved in 2-phenoxyethanol ~ 8.0 19.4 para-toluenesulfonic acid (transetherification catalyst) dissolved in 2-phenoxyethanol 4.8 11.7 phenothiazine 0.1 0.1 aqueous dimethylamine 97.8 244.6 2-phenoxyethanol 200.0 methyl ethyl ketone 150.0 l~olyglycidyl ether of Bisphenol A having a molecular weight of about 380 and an epoxy equivalent weight of about 190 commercially available f~om Shell Chemical Company.
* This symbol designates a trade mark throughout the disclosure ~3~3 The EPON 879 and Bisphenol A were char~ecl into a reaccion vessel under a nitrogen ~tmosphere and heated to l'iOC. to mitiate an exotherm. Following the 20-minute exotherm, ~he reaction mixture was held for about one hour at 150C. Thi5 material WclS then added over 15 S minutes to a mixture of trimethylolpropane and stannous c~loride which had ~een heated under nitrogen to 200C. The resin wa~ then heatacl at 190C. for ~wo hours, cooled ~o 150G. and then thinned with dibenzyl ether. At 135~C., the N-butoxyme~hylacrylamide, pheno~hia~ine and solutions of hydroquinone and para-toluenesulfonic acid were added.
Ihe stirred mixture was held at 120-135C. for 40 minutes during which time ~he pressure was gradually reduced to approximately 6 torr and 195 parts of n-butanol was distilled off. The evacuated reaction vessel was reCurned eO a~mospheric pressure wi~h ni~rogen and the mixture was thinned immediately with 2-phenoxyethanol then with methyl ethyl ~etone after cooling to 100C. ~hen the resin had cooled to 80C., aqueous dimethylamine was added over 30 minutes. Finally, the mixture was stirred at 80~C. for two hours Lo complete the preparation.

xample II
The Michael adduct of Example I was neuLralized with lactic acid and dispcrsed in deioaiæed water to form a 32.4 percent by weight aqueous dispersion. The charge for preparing the aqueous dispersion was as follows:
Ingredient Michael adduct of Example I 244.2 (73.7~ Resin Solids) 88% aqueous lactic acid 22.5 deioniæed water 350 3~L3~ 3 Untreated and zinc phosphated steel panels were dipped into this aqueous dispersion, removed and the dip coatings baked at 400F.
(204C.) fo~ 30 minutes ~o form a solvent-resistant, ~ard,.smooth, dark film of approximately 3 mils thi~kness. One hundred (100) acetons double rubs slightly softened the film.

Exa~le III , The aqueous dispersion of Example II was thinned wi~h deionized water to form a 10 percent resin solids electrodeposition bath.
Th~ dispersion had a p~ of 6.6. Both untreated steel and zinc phosphated steel panels were cathodically electrodeposited in the dispersion at 150 voLts for 90 seco~ds to produc~ insulating fi1ms.
Ihe appearance of the films was good and adhesion to the substrate was excellent. When the fi1ms were baked at 450F. (232~C.~ for 30 minutes, light-colored, hard films were obtained. The film build over the ur,treated steel panels was 0.6 mil, wherea~ over the zinc phosphat~d panels, it was 0.3 mil.
When baking was conducted at 4Q0F. ~2Q4C.) for 30 minutes, light, non-tacky films resulted which were, however, somewhat soft.

~3~3 F.x~ le IV
The Michael adduct oE R:~am?:Le :~ was mixed with an amine-aldehyde crosslinker con~ercially available from American C:yanamid Company as CY~IEL 1156 at a level of 20 percent Oll total solids7 partly neutralized with lactic acid to 85 percent of total neutra'lza~ionj and dispersed in deionized water to form an aqueous coating composition. T~e charge for preparing the composition was as follows:
Ingredient Parts by We.Lght Michael adduct oE Example I 244.2 CYM~. 1156 45.0 88% aqueous lactic acid 22.5 deionized water 350.0 Untreated steel and zinc phosphated steel panels were dipped in the bath, removed and baked at 400F. (204C.) for 30 minutes to form hard, solvent-reslstant films (0.8 mil over untreated steeland 0.4 mil over zinc phosphated steel). One hundred (100~ acetone double rubs did not affec~ the fil~s.
When the coatings were baked at 350~. (177C.) for 30 minutes, the baked films (about 1.7 mils over untrea-ted steel and about 2.0 mils over the ~inc phosphated steel) were hard and acetone resistant in that 100 acetone double rubs were required to slightly soften the films.

`~' - 20 _ _ ~ . .. . .. . . . . .

Exam ~
~he Michael addtlct of Example I Wa3 co~bined with CYMEL 1156 *
at il 1evel of IS percent on total soLids, pnrtly neutrali~ed with lartic acid, and dispers~d in deioni~ed water to form an aqueous electrodeposition bath_ ~he charge for preparing the bath was as fo11Ows:
Ingredien~ Parts by Wei~ht Michael adduct of Example I244.2 CY~EL 1156 3l.8 88% aqueous lactic acid 22.5 deionized water 2017.5 The dispersion wafi excellent and had a pH of 7Ø Both untreated steel and zinc phosphated steel panels wer~ electrodeposited in the bath at 150 volts (for untreated sceel) and 200 ~olts (for zinc phosphated steel) Eor 90 seconds to produce insulating films. The appearance of the films was good and the adhesion to the substrate was e~cellen~. When the wet films ~ere bak~d at 375F. ~L91C.) for 30 minutes, hard, light-colored, glossy, solvent-reslstant films were obtained. On~ hu~d-~ed (100) acetone double rubs only slightiy softened the film.
When the example was repeated and the CYMEL 1156 c~ncentration raised to 20 percent by weight, insulating film~ were ob~ained which had excellent appearance and excellent adhesion to the substrate. Whe~ the wet films were baked at 350F. (177C.) for 30 minutes, baked films (1.3 mils on untreated steel and 0.5 mil on ~inc phosphated steel) which were light in color, soft and ~omewhac tacky were obtained. Howe~er, the sol~ent resistance of the films was excellent in that 100 acetone double rubs only slightly softened the film. When the baking temperaCure was raised to 400F. (204C.) for 30 minuces, Che baked Eilms (0.9 mil ~ 21 ~

~ :~ ~3 ~

for untreated steel and 0.5 mil Eor zinc phosphated steel) were light in color, hard, glossy, smoo~h and solvent-resistant. One hundred (100) acetone double rubs did not affect the films.

Rxample VI
The Michael adduct of Example I was combined with a capped isocyanate crosslinker at a level of 20 percent on to~al solids, partly neutralized with lactic acid, and dispersed in deionized water to form an aqueous coating composition. The charge for preparing the composition was as follows:
In~redient Parts by Weight ~ichael adduct of Example I 244.2 capped isocyanate crossllnkerl (75~ solids in 2-ethoxyethanol) 60.0 8S% by weight aqueous lactic acid22.5 deionized water 350-0 dibutyltln dilaurate 2.9 lCapped isocyanate crosslinker was formed from reacting one- mnle of trimethylolpropane with 3 moles of the 2-ethylhexanol monourethane of toluene diisocyanate.
Untreated steel and zinc phosphated steel panels were dipped in the aqueous dispersion, removed and baked at 350F. (177C.~ for 30 minutes.
The baked film (about 2.5 mils) was brown, smooth, glossy, hard and solvent-resistant in that 100 acetone double rubs only slightly sotened the film.
When baking was conducted at 400F. (204C.) for 30 minutes, similar films were obtained but which were more solvent-resistant in that 100 acetone double rubs did not affect the film appearance.
Fxample VII
The aqueous dispersion of Example VI was thinned with additional deionized water to form a 10 percent resin solids electrodeposition bath.

~3~

The dispersion ~as excellen~ and h~d a pH of 6.6. Untreaced steel and zinc phosphated steel panel~ were cathodically electrodeposited in this bath ac lO0 volts for 30 seconds to form insulating films having a fair appearanee and excellent adhesion to the substrate. When the ~ilms were baked at 350~F. (1.77C.) for 30 minutes, ba~d ~i1ms Qf about l.0 mil in thickness ~ere obtained which ~ere yellowish in appearance, smooth, glossy, hard and solvent-resistant in that lO0 acetone double ruhs only slightly softened ~he ~ilm.
When the wet films were bakecl at 400~F. (~04C.) for 30 minutes, the acetone resistance of the film was enhanced in that lO0 acetone do~ble rubs did not affect the film appea~ance.

~ VIII
A Michael adduct prepared as gene~ally described in Example was combined with.a butylated urea-formaldehyde condensate ac a level of 30 percenc on ~otal solids, partly neutr~lir-ed with lactic acid and dispersed in dei~ni~ed water.to form an elec~rodeposi~ion bath. The charge for preparing the ba~h was a~ follows:
Ingredienc Parts by Wei~ht ~ichael adduct of Example I .
(74.5% resin solids.) 188 butylaeed urea-formaldehyde condensatel (100% total solids) 60 88% by weight aqueous laccic acid 14.0 deionized ~a~er 1740 lCo~ercially available from American Cyanamid Company as BEE1~ 80.
Untreated, zinc phosphated and galvanized steel panels.~ere electrocoated in the bath at ~50 volts for 90 seconds to form insuiating ~3~3 ~ilms ~aving good appearance and good adhesion to the metal substrate.
Fllms baked at 328F. (165C.) for 30 minutes were hard and required 40 acetone double rubs to remove the film. A slight~y higher bake, 347F.
(175C.) for 30 minutes, led to increased solvent resistance. Eighty (80~ to lO0 double rubs were required to remove ~he film. Film thickness in all cases was 0.6-0.8 mil. All films were essen~ially colorless.

Exam~le IX
The Michael adduct of Example I was neutralized with lactic acid and dispersed in deioniæed water to form a 10 percent resin solids electrodeposition bath. The charge for forming the bath was as follows:
Parts by Weight Michael adduct of Flxample I 285.3 88% by weight aqueous lactic acid solution 8.0 deionized water 1576.7 The dispersion was good and had a pl~ of 4.6. Untreated aIId zinc phosphated steel panels were electrodeposited in this bath a~ 200 volts for gO seconds to form insulati-.lg films. The appearance of the wet films was good and adhesion to the substrate was e~cellent. When the ilms were baked at 400F. (204C.) for 30 minutes, film thicknesses oE 1.0 mil on the untreated steel panels and 0.4 mil on the æinc phosphated steel panels were obtained. The ilms were slightly dark, smooth and tack-free although acetone easily removed the films from the surface of the panels. When the films were baked at 450F. ~232C.) for 30 minutes, thicknesses of 0.5 mil on the untreated steel panels and less than 0.1 mil on the zinc phosphated steel panels were obtained. The coatings were smooth, somewhat dark in color and tack-free. The coatings on the untreated steel panels were somewhat ~3~a8~

solvent-reslstant in ~hat 30 acetone double rubs were required to remo~e the 11ms from the surfaces. The films bullds on the zinc phosphated steel panels wer& too ~hin to measure acetone resistance.
Comparative Example X
For the purposes of compari.son~ an aqueous electrodeposition bath similar to that of Example V was prepared but in ~hich the nitrogen was not incorporated into the polymer via a Michael addit:ion. Instead, an epoxy-containing resinous material was reacted with secondary amine to incorpor~te the nitrogen into the polymer through an amine-epoxy reaction. The bath contained 10 percent resin solids of which 15 percent was a~inoplast (CYM~L
1156). The charge for preparing the pol~mer was as follows:
In~redient Parts by Weight PCP 0200~ 07 15 xylene 351 Bisphenol A 1224 benzyldimethylamine 8.5 ben~yldimethylamine 14.9 2-ethoxyethanol 1231 20 diethylenetriamine diketimine2 396 methylethanolamine 317 A polycaprolactonediol (molecular weight 530) commercially available from Union Carbide.
Condensation product of one mole of diethylenetriamine and two molec 25 of methyl isobutyl ketone in excess methyl isobutyl ketone (73 percent by weight solids).
* *
The EPON 828, PCP 0200 and xylene were heated to reflux in a rPaction vessel equipped with a nitrogen sparge tube and a Dean-Stark trap to collect water. After one-half hour of reflux, the mixture was ``.1~' ` _ 25 _ cooled Erom 200~C. to l50~C. and the ~isphenol A and first portion of benzyldimethylamine were added. Heating was;discontinued as the mixtu~e exother~ed for L0-20 minutes. The mixture was then cooled to 130UC. and the second portion of benzyldimethylamine ~as added. The mixture was then stirred at 130~C. until a Gardner-Holdt viscosity of a l:l mixture with 2-ethoxyethanol reached ~ (two hours). The 2-ethoxyethano1 was then added to the resln along with the amines. The reaction was completed by holding the mixture at 110C. for one hour.
The epoxy-amine adduct prepared as described immediately above was combined with C~MEI. 1156, neutrali~ed with acetic acid and di~persed in deionized water in tha following charge to form a lO percent resin solids electrode~osicion bath containing 15 percent by weight aminoplast crosslinker.
Ingredient Solids Parts by Weight epoxy-amLne adduct 170.0 215.0 CY~EL 1156 30.0 30.0 acetic acid 2.17 ~o17 deionized water - 1775 0 Zinc phosphated steel panels were cathodically electrodeposieed in this bath at 20~ volts ~or 90 seconds and the wet films baked under the conditions sho~n in the table below. The films were then evaluaced for hardness, acetone resistance and color, and compared to films electrode-posited from the bath of Example V.

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rr 3 C_ C
tD fD U~ rtrr rr rr r~ C
rt ~ C:~
rr IJ- rr 5 ~ ~ ~ ~ r~
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rr ~ O g gu: C~ o r oq rf g ~ t n ~ ` o Q.
cr~ O p P p~ rr ~ p ~D C O O O OP~ ~ P~
G p p p pQ tt~e~ ~t Qt ~ o n Q`q rt~ P
tt ~ ~ r~
rr ~ 0 . ~ rrrt rtrr ~ rr (D ~ ~ ~~ ~ C
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Claims (11)

1. THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
   PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
   
   l. A heat-curable resinous binder dispersible in aqueous medium with the aid of cationic salt groups and electrodepositable on a substrate comprising the Michael-type reaction product of:
   (A) an active hydrogen-containing polymeric material containing alpha, beta-ethylenically unsaturated moieties in conjugation with moieties with (B) a primary and/or secondary amine having a boiling point below 100°C;
   said reaction product being treated with an acid to provide said cationic salt groups and being in combination with a curing agent which 16 reactive with the active hydrogens at elevated temperatures to form a crosslinked product.
2. 2. The resinous binder of claim l in which the cationic salt groups are amine salt groups.
3. 3, The resinous binder of claim 1 in which the polymeric material (A) is formed from reacting a polymeric polyol with an N-alkoxymethyl-containing acrylamide or methacrylamide.
4. 4. The resinous binder of claim 3 in which the polymeric polyol is derived from a hydroxyl-containing epoxy resin.
5. 5. The resinous binder of claim 1 in which the polymeric material (A) contains active hydrogens selected from the class consisting of hydroxyl, thiol, primary amino and secondary amino.
6. 6. The resinous binder of claim 1 in which the curing agent is selected from the class consisting of aminoplasts and capped isocyanates.
7. 7. A method of electrocoating an electrically conductive surface serving as a cathode which comprises passing electric current between said cathode and an anode immersed in an aqueous dispersion of an electrodepositable heat-curable resinous binder comprising the Michael-type reaction product of:
   (A) an active hydrogen-containing polymeric material containing alpha, beta-ethylenically unsaturated moieties in conjugation with moieties with (B) a primary and/or secondary amine having a boiling point below 100°C;
   said reaction product being neutralized with an acid to provide said cationic salt groups and being in combination with a curing agent which is reactive with the active hydrogens at elevated temperatures to form a crosslinked product.
8. 8. The method of claim 7 in which the polymeric material (A) is formed from reacting a polymeric polyol with an N-alkoxymethyl-containing acrylamide or methylacrylamide.
9. 9. The method of claim 8 in which the polymeric material (A) is hydroxyl-containing epoxy resin.
10. 10. The method of claim 7 in which the polymeric material (A) contains active hydrogens selected from the class consisting of hydroxyl, thiol, primary amino and secondary amino.
11. 11. The method of claim 7 in which the curing agent is selected from the class consisting of aminoplasts and capped isocyanates.